The proposed work is designed to measure the important membrane coefficients (i.e. permeability coefficients, hydraulic conductances and reflection coefficients) that have previously been measured in dentin in vitro, in vivo, in dog dentin. Further, by simultaneously measuring isotope clearance rates simultaneously from the buccal and lingual surfaces of the same tooth, we will be able to determine the influence of changes in external hydrostatic or osmotic pressures on pulpal pressures and the rate at which substances permeate through dentin to the pulp. We will attempt to estimate pulpal interstitial fluid tracer (or drug) concentrations and the influence of chemical concentration and/or the incorporation of vasoconstrictors with the solute, on those concentrations. The in vivo reflection coefficients of a variety of solutes and solvents of dental interest will be measured before and after dentin surface manipulations.